Myriad of power tools (including pneumatic or electric types) are available now on the market. In order to provide multiple functions through a single power tool, a removable power tool spared a distal end with a shaft to couple with varying types of application tools (such as grinding wheels, sleeves, etc.) has been developed to allow the power tool to change application tools to switch functions as desired. This creates a structural problem of assembling and disassembling the application tools. In the event that the application tools are not firmly assembled, operation safety becomes a great concern. However, a firmer installation and assembly structure often requires a greater effort to assemble or disassemble the application tools.
In order to provide a firmer fastening structure and fast disassembly of application tools, fast disassembling apparatus has been proposed in prior art. For instance, R.O.C. patent No. M333481 entitled “Fast assembling and disassembling fastening apparatus” comprising an outer ring, a clutch disk, a first spacer, a second spacer, a plurality of steel balls, a plurality of compression springs and a latch disk. The outer ring has an inner space in the center. The first spacer and second spacer are located in the inner space opposing to each other. The latch disk and clutch disk are coupled at two sides of the outer ring to clamp the first spacer and the second spacer. The first spacer has a plurality of first protruding portions. The second spacer has a plurality of second protruding portions. The steel balls are located between the first protruding portions and the second protruding portions. Each of the compression springs has two ends respectively butting the back side of the first and second protruding portions. The fastening apparatus is run through by an output shaft of a power tool. The output shaft has a distal end coupled with an application tool. The fastening apparatus provides a packing force to form a firm coupling between the output shaft and the application tool. The latch disk has a plurality of notches thereon. When the outer ring is turned by a user, the steel balls can be driven to drop into the notches to release the packing force among the clutch disk, latch disk and output shaft so that the user can quickly separate the output shaft and the application tool.
R.O.C. patent No. M349437 also discloses a similar technique. While they provide fast disassembling effect, they contain a great number of elements. Moreover, the first spacer, second spacer and compression springs form uneven forces during assembly that make assembly difficult. More assembly time is needed and element costs also are higher.